Photographic color correction process



Oct. 10, 1944. R M. EVANS 2,350,213

' PHOTOGRAPHIC COLOR OOBRECTION PROCESS I Filed Jan. '28, 1942 2 Sheets-Sheet 1.

FIG].

= Hag; BLUE SENS/T/VE I? #GREEN SENSITIVE FPED SENSITIVE (2 SUPPORT FIG. 2;

BLUE GREEN "RED YELLOW MAGENTA CYAN GRAY FIG. 3.

RALPH M. EVANS INVENTOR BYE v A (Jet 10, 1944. I R. M'EvA s 2,360,213

PHOTOGRAPHIC COLOR CORRECTION PROCESS I Filed Jan. 28, 1942- 2 Sheets-Sheet 2 ATTORNEYS Patented Oct. 10, 1944 Fries PHOTOGRAPHIC COLOR CORRECTION PROCESS Ralph M. Evans, Rochester, N. 31., asslg-nor to Eastman Kodak Company, Rochester, N. Y., a

corporation of New Jersey Application January 28, 1942, Serial No. 428,580 6 Claims. ('01. sis-2) This invention relates to processes of subtractive color photography, and more particularly to color correction processes of subtractive color photography.

In the production of pictures in natural color in photographic films of the multilayer type, the successful reproduction of a colored object has always depended upon the proper balance of variables such as emulsion sensitivity, development,

and the color of dyes or pigments of which the final picture is composed. 'Defects inthe color of the final picture are generally attributable to improper balance of such variables, and are -manifest by the predominance of, or the lack of,

one or more colors in the pictures.

In photographic color processes of the bleachout type, utilizing multilayer films having difage from black-and-white development in one layer influences bleaching of the dye in an adjacent layer, rather than confining its activity to its own layer. The eflect of this is to cause a bleaching of dyes in areas of the adjacent layer where bleaching should not occur, and at the same time, the silver image in the one layer loses its efiiciency for influencing the bleaching of dye in its own layer. A similar effect has been observed in multilayer color films which are processed by well-known color-forming development methods.

The object of the present invention is to provide a method of compensation for the adverse effect of an image in one layer of a subtractive color film, upon the formation of a colored image in an adjacent layer. Other objects will appear hereinafter.

These objects are accomplished by using the aforesaid silver image to control the sensitometric'characteristics of said adversely afiected 7 layer in the manner to be subsequently described.

' Fig. 2 shows the range of tones of several different colors in a colored original.

Fig. 3 is a representation, when the gray scale is balanced, of the theoretically desired gammas and the effective gammas of silver images in bleaching dyes in a film which has been exposed to the colored object of Fig. 2 and developed black-and-white.

- under influence of silver images inthe layers, it

Fig. 4.is a representation of the effective gammas of silver images, beforeand after balancing the gray scale, in bleachih dyes in a film which has been exposed to the colored object of Fig. 2 and developed black-and-white.

Fig. 5 is a representation of the method of the invention, showing the effect on the eiiective gammas of the silver images, before balancing the gray scale, of exposing through the top layer silver image and forming a secondary silver image in the middle layer and thereafter bleaching dyes in the region of all of the silver images.

My invention will now be more fully described with particular reference to the accompanying drawings.

The film shown in Fig. 1 may be composed of the materials and be sensitized, colored and processed, as described in Ehrenfried U. S. Patent 2,322,001, granted June 15, 1943, or Seymour U. S. Patent No. 2,231,685, granted February 11, 1941. That is, a support l0 may have coated thereon, in order, red, green, .and blue lighte sensitive emulsion layers, H, l2, and i3, colored with dyes roughly complementary to the ef- :fective sensitivity of the respective emulsion layers; layer H being colored cyan, layer i2 colored magenta, and layer l3 colored yellow. After exposure to an original having the colored images shown in Fig. 2, the film is de- 'apparance of the film after development. In the figure, the solid H and D curves represent the theoretically desired gammas of the silv'efimages in the different layers, produced by exposure of the film to light of the color shown in the squares of Fig. 2 directly above the. respective curves, followed-by development, which gammas in subsequent bleach-out treatment of the fllm 5 would efiect the correct amount of bleaching of the dyes to give a balanced gray scale. The dotted H and D curves represent the observed effective gammas of the silver images in bleaching dyes, and these curves indicate that the gammas of the silver images in layers ii and ii are approximately those theoretically desired, whereas, in layer ii there appear effective gammas in areas corresponding to exposure with blue and magenta llghtfrom the colored object; the efl5 fective gammas corresponding to exposure with green and yellow lights of the object are .low. Accordingly, the efiect of bleaching dyes from the respective layers under influence of the effective silver gammas, is to place green over the blues and yellows, a darkening of the greens and a lightening of the magentas. These are typicaldefects in color-rendition with which my inven tion' is concerned, and which-may be attributed,

in the case illustrated, to the eifect of the silver image in layer i3 upon the bleaching of dyes in the adjacent layer l2.

I have reasoned that the effective gammas of the silver images, shown by the dotted H and D curves of Fig. 3, before balancing the gray scale,

must have had the approximate characteristics shown by the solid H and D curves in' Fig. 4,

' wherein, as before, the dotted lines represent the respect that the density of the dye, or the thickness of the emulsion, in the middle layer is greater (shown in Fig.4 as an emulsion layer. of greater thickness) and expose the film to a colored object such as shown in Fig. 2. Thereafter, silver images are developed in the respective emulsion layers using a suitable black-and-white developer. As explained above, I have reasoned that at this point the respective games of the silver images in the layers will have the characteristics shown by the solid H and D curves in Fig. 4.

Since, at least a portion of the respective gammas of the silver images in the middle layer may be attributed to the effect of the top layer silver image on the bleaching of dye in the middle layer, the middle layer is given a partial exposure with The dot-dash lines show the overall effective gammas of all of the silver images for bleaching dyes in the middle layer, when the silver images in layers It and i1 effect the correct amount of bleaching in their respective layers.

In other words, in the areas of the middle layer adjacent to the er images of the top layer, have been impre d secondary silver images of opposite gammas, ml in areas of the middle layer not adjacent to top layer silver, images of uniform density have been formed. When the dyes are bleached from the layers aadescri'oed above, independent of the silver images therein, so that the gray scale is balanced, dye images are left in the areas of layers l5, l6, and I! indicated by shading. The process, therefore, has

faithfully reproduced the colors of the original object since the effective gammas of the silver images shown by the dot-dash lines of layer i6- 'of dyes from the layers as shown by the solid line gammas of Fig. 3. It is also apparent that In a manner similar to that-described above,

my invention may be applied to the case where it is found that the silver image in the bottom layer is adversely effecting bleaching of the dye in the middlelayer. However, in this case the corrective exposure is made through the bottom la er silver image. I

My process is also applicable to multilayer color films of the type having dyed emulsion layers sensitized to light of wave lengths transmit- .ted by the emulsion ayes. For instance, a film having green, red and blue sensitive emulsion layers, colored respectively cyan, yellow and magenta, wherein the magenta layer is over the yellow layer and the cyan layer is below the yellow layer, and in which colored images are formed by the bleach-out process, may be treated I by my method. In this fllm where defects in color-rendition may be attributed to the influnce of themagenta layer silver image on the bleaching of dye in the adjacent yellow layer,

the defects in color-rendition may be manifest by a bluing of the greens, darkening of'the blues, yellowing of the reds and a lightening of the yellows when the gray scale is balanced. To

compensate for this, after negative development the middle layer is given a partial exposure through the top layer silver image and a secondaryimage is developed therein. Hereafter, the dyes in the respective layers are bleached out under influence of silver images in them, by

, titans of suitable dye- In correcting for faulty color-rendition in flims of the .type described, and others useful in'the green light through the silver imagein the top layer and a secondary black-and-white image is developed therein. Thereafter, the' dyes arebleached from the layers under influence oi. silver images therein by use of a bleaching solution The reason for using an increased amount'of magenta dye in the middle layer and developing a secondary image in the-layer, is now apparent from consideration of 5. As in'Fig. 4, the' and i1 indicate the effective gammas of the silver images before the secondary image was deas disclosed in U. S. Patent'2,322,001, above cited.

. solid H and D curgves in emulsion layers II, It, 0

bleach-out process, practically the only limitations to which my method subject, is the case where it isfcund to be impossible to m e the necessary s plementary exposure into adversely ail d layer'through the image causing the adverse effect, due to the presence of an overlying silver image or dyed layer. a p

Where it is found that the middle layer image of a fllm of the type shown in Fig. 1 is adversely affecting bleaching ofthe dye in either of the other adjacent layers, the image of the aspect not involved may be printed and developed in the film subsequent to the supplementary exposure,

of the adversely affected layer.

Whereas, my invention has been described ondary silver image formed in the middle layer. respect to faulty rendition of all shades of 61.

ors of the colored object of Fig. 2, from the pure color to black, similar defects in rendition of the tints of the colors from the pure colors to white are observable, and may be compensated for in the manner of my invention as described previously or subsequently hereto.

My invention may also be applied to reversal processes -of subtractive color photography wherein colored images, are produced by means of color-forming development. Typical films useful in such processes, are those disclosed in Mannes and Godowsky U. S. Patent U. S. 2,252,718, granted August 19, 194-1, and Jelley and Vittum U. 5. Patent 2,322,027, granted June 15, 194.3. In these processes certain color-rendering defects are attributed to the effect of the silver image of first development in one layer, on thecolor-development of a colored image in an adjacent layer. Where the observed defect is of the same order as observed in the processes of the bleach-out type, the correction is applied in the same general manner as previously described,

after first development, by exposing the adverse-" The color corrected films, corrected in the manner described in the invention, may be used as color transparencies for projection, viewing or the like, or these films may be used for printing other pictures in color. For instance, one may print the corrected films onto sensitive films of the same type and apply the color correction methods of my 1 ention for producing color balanced images the final copy. Similarly, in processes where it is desired to take separate aspects from a color film and later assemble colored images corresponding to these aspects, these aspects may be taken from color. films corrected for deficiencies in absorption or transmission of subtractive dyes, may be used in conjunction with than in the developer, any requirement of inin order upon a support, red, green and blue sensitive emulsion layers, in which are to be developed, respectively, cyan, magenta and yellow dye images. Here it is observed that the negative silver of the bottom layer has an adverse effect upon the development of a dyeimage in the middle layer, which corresponds, 'efiectively,

layer adjacent to the silver images of the bottom layer. In other words, there is a tendency in colortorming development of the middle laymy processes.

It is to be understood that the disclosure here in is by way of example and that I consider as included in my invention all modifications and What I claim is:

1. In a process of producing subtractive multicolor pictures in a photographic film'carrying superposed dyed silver halide emulsion layers sensitized to record different regions of the spectrum, wherein the emulsion layers are exposed, developed and the dyes should be removed only under influence of, and in the region of, silver images in the respective layers, but wherein a developed image in the exposed area of one layer adversely affects removal of dye in an adjacent layer, the method comprising exposing to a colored object, a film of the type described having an increased amount of dye in said ad- 7 image in said re-exposed layer and then removing the dyes under the influence of silver images in both layers.

' 2. In a process of producing subtractive multlcolor pictures in a photographic film carrying superposed silver halide emulsion layers sensito insufficient "exposure in areas of the finiddle' tized to record difierent regions of the spectrum and dyed complementary to the sensitivity thereer, towards formation of more'magenta dye than is required. The method of compensating for this defect consists, after first development of silver images in the layers and their removal from the layers, of reversal exposure and development of the cyan image in the bottom layer, followed by supplementary exposure of the middle layer through .the cyan silver and dye image,

followed by development of a secondary silver' image therein, and finally reversal exposure and color development of the other layers.

The adverse effect may also be compensated for by giving the bottom-layer a prolonged re versal exposure to red light after first development. which, due to slight sensitivity of the mid-. dle layer to red'fig'ht will impress a supplemenall layers by means of color-forming development.

of, wherein the emulsion layers are exposed, de-

veloped and the dyes should be removed only therein, partially exposing the unexposed area of said a versely affected layer through the' image in said other layer, said exposure being just suificient to remove all, of, the increased amount of dye in those regions of said adversely -,affected layer which underlie regions free of -in both layers. a I I 3. In a process of producing subtractive multi color pictures in a'photographic' film carrying silver, in said one layer, developing a second image'in said re -irposedlayer and the'n'removing the dyes .under influence of the silver images sup rposed silver halide femulsion'layers sensitized to record diflerent regions 01' the spectrum, and dyed complementary to the sensitivity asegaais color pictures in a photographic film carrying thereof, wherein the emulsion layers are exposed,

' developed and the dyes should be removed only under influence of, and in the region of, the

I silver images in the respective layers, but wherein'a developed image in the exposed area of the outer emulsion layer adversely aifects removal of dye in, an adjacent layer, the method comprising exposing to a colored object, a film of the type described having an increased amountof dye in said adversely affected layer, developing silverimages therein, partially exposing the unexposed area of said adversely afiected layer through the image in said other layer, said exposure being Just sufllcient to remove all of the increased amountof dye in those regions of said adversely afl'ected layer which underlie regions free of'silver in said outer emulsion layer, developing a second image in said re-exposed layer and then removing the dyes under influence of the silver images in-both layers.

4. In a process of producing subtractive multi- 'color pictures in a photographic film carrying in order upon a support, red, green and blue sensitive silver halide emulsion layers colored cyan, magenta and yellow, respectively, wherein the emulsion layers are exposed, developed and the dyes should be removed only under influence of, and in the region of, silver images in the respective layers, but wherein a developed image in theexposed area 01 the yellow layer adversely aflects removal of dye in the magenta layer,

the method comprising exposing to a colored oblect, a fllm of the type described having an increased amount of magenta dye in the green sensitive emulsion layer, developing silver images therein, partially exposing the magenta layer with green light through the image in the yellow layer, said exposure being'just sufllcient to remove all of the increased amount of magenta dye in those regions of said magenta layer which underlieregions free of silver in said yellow layer, developing a second image in themagenta layer and then'removing the dyes underinfluence of the silver images in both layers.

5, In a process of producing subtractive multisuperposed dyed silver halide emulsion layers sensitized to light transmitted by the emulsion layers, wherein the emulsion layers are exposed,

developed and the-dyes should be removed only under influence 01, and in the region of, silver images in the respective layers, but wherein a developed image in the exposed area of one layer adversely afiects removal of dyes in an adjacent layer, the method comprising exposing to a col-- ored object, a film ofthe type described having an increased amount of dye in said adversely affected layer, developing silver images therein, partially exposing the unexposed area of said adversely affected layer through the image in said other layer, said exposure being just suflicient to remove all of the increased amount of dye in those regions of said adversely afiected layer which underlie regions free of silver in said one layer, developing a second image in said re-exposed layer and then removing the dyesunder influence of silver images in both layers.

6. In a process of producing subtractive multicolor pictures in a photographic film carrying superposed dyed silver halide emulsion layers l sensitized to light transmitted by the emulsion layers, wherein the emulsion layers are exposed,

developed and the dyes should {be removed only under. influence of, and in the region of, the

silver images in the respective layers, but wherein adeveloped image in the exposed area of the outer emulsion layer adversely aflects removal of dye in an adjacent layer, the inethod comprising exposing to a colored object, a film of the type described having an increased amount "of dye in said adversely affected layer, developveloping a second image in said re-exposed layer and then removing the dyes under influence of th silver images in both layers.

RALPH M. EVANS. 

